Powered air cleaning system and air cleaning method

ABSTRACT

A powered air cleaning system ( 31 ) and air cleaning method are disclosed. The system comprises a flow path ( 22 ) extending through the system from an air inlet ( 4 ) to a clean air outlet ( 5 ). A motor-driven fan ( 24 ) located along the flow path draws particulate debris laden air into the inlet and rotates it about an axis (A-A) to form a rotating flow that stratifies the debris laden air with the heaviest particles in the outermost orbits of the rotating flow. An ejector port ( 33 ) is provided for ejecting particulate debris laden air from the stratified rotating flow in the system to the environment. An air filter ( 9 ) located within the rotating flow and across the flow path upstream of the outlet filters air from the innermost orbits of the stratified rotating flow. The motor-driven fan is operated to maintain a positive air pressure in the system on the filter even with cyclic air flow demands so that the rotating air flow continually sweeps the outside surface of the air filter to minimize buildup of debris on the filter.

RELATED APPLICATIONS

This application is a U.S. national stage application under 35 U.S.C.§371 of pending international application number PCT/US03/10238 filedApr. 4, 2003, which in turn is a continuation in part application ofinternational application PCT/US02/33220 filed Oct. 18, 2002 whichdesignated the U.S. and claimed priority of U.S. provisional application60/329,748 filed Oct. 18, 2001.

TECHNICAL FIELD

The present invention is directed to an improved powered, atmosphericejective, air cleaning system and air cleaning method for efficientlyremoving debris from debris laden air to supply clean air to a devicewith which the system is used. For example, the invention is useful inconnection with total air flow applications such as ventilation systems,as a fixed air flow provider for heat exchangers and heating and airconditioning systems, and with devices having a variable air flowdemand, particularly internal combustion engines which exert a variablevacuum on their air intake to be supplied with clean air.

BACKGROUND AND SUMMARY

Air intakes that centrifugally separate heavier-than-air particles fromthe air to be used in internal combustion engines, ventilation systems,and other apparatus that draw in air laden with debris, are known. Theuse of in-line filters in air delivery systems to clean the air is also,per se, known. However, air filters are subject to plugging by debrisfrom the air passing through the filter, which eventually increases therestriction to air flow through the filter and decreases the operatingperformance of an associated device, such as an electronicallycontrolled internal combustion engine being supplied with air throughthe filter. Frequent filter replacement and shorter service intervalsmay also be required, which increases the cost of operation. There is aneed for an improved air cleaning system and air cleaning method whichcombine centrifugal separation and air filtration in a manner toefficiently remove debris from debris laden air while reducing oravoiding the aforementioned problems.

A powered air cleaning system according to the invention comprises aflow path extending through the system from an air inlet to a clean airoutlet. A motor-driven fan is located along the flow path to drawparticulate debris laden air into the inlet and rotate it about an axisto form a rotating flow that stratifies the debris laden air with theheaviest particles in the outermost orbits of the rotating flow. Anejector port is provided for ejecting particulate debris laden air fromthe stratified rotating flow in the system to the environment. An airfilter is located within the rotating flow and across the flow pathupstream of the clean air outlet for filtering air from the innermostorbits of the stratified rotating flow. According to the disclosedexample embodiments of this invention, the filter is elongated in thedirection of the axis about which the debris laden air is rotated. Anouter peripheral surface of the filter within the rotating flow is sweptby innermost orbits of the stratified rotating flow for minimizingdebris buildup on the filter.

An air cleaning method of the invention comprises drawing particulatedebris laden air into the air cleaning system with the motor-driven fanlocated in the system, forming a rotating flow of the debris laden airin the system to stratify the flow with the heaviest particles in theoutermost orbits of the rotating flow, flowing air from the innermostorbits of the rotating flow through the filter enroute to the outlet ofthe system, and returning particulate debris laden air from thestratified rotating flow in the system to the environment. According tothe example embodiments air is supplied to a device with a variable airflow demand, which applies a variable vacuum to the outlet of the aircleaning system, and the method further includes operating themotor-driven fan to maintain positive air flow pressure in the system toreturn particulate debris laden air to the environment from the systemat all rates of air flow demand by the device. The positive air flowpressure, acting on the filter of the system located within the rotatingflow, keeps debris buildup on the filter to a minimum. Accordingly, thesystem self-cleans its air filter.

In one example embodiment, the ejector port of the system is locatedradially outward of the outermost orbits of the rotating flow, in theform of an ejector slot which extends the length of the air filter. Thisarrangement helps in subjecting the air filter to a slight positivepressure, reducing restriction to the engine or apparatus the aircleaning system is installed on and aiding the self cleaning of the airfilter.

These and other features and advantages of the present invention willbecome more apparent from the following description when taken inconnection with the accompanying drawings, which show, for purposes ofillustration only, two example embodiments in accordance with thepresent invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view from the front, inlet end, and to one side,of a powered air cleaning system/apparatus according to a first, exampleembodiment of the present invention.

FIG. 2 is a perspective view from the back, outlet end, and to one side,of the air cleaning system of FIG. 1, shown, schematically, connected toan air intake of a device with a variable air flow demand.

FIG. 3 is a view of the system similar to FIG. 1 with portions of thehousing cut away to show components within the housing.

FIG. 4 is a view of the system similar to FIG. 2 with portions of thehousing cut away to depict components inside the housing.

FIG. 5 is a view of the system like FIG. 1 except with a portion of thehousing removed and with the filter in the system removed to show theclean air outlet orifice through the back, outlet end of the housing.

FIG. 6 is a perspective view of the system like FIG. 1 but with thedetachable motorized fan housing and filter housing forming the systemhousing being separated from one another.

FIG. 7 is a detailed view of a portion of the joined detachablemotorized fan housing and filter housing having a removable joining clipthereof as shown in FIG. 5.

FIG. 8 is a perspective view from the front, inlet end, and to one side,of the detachable motorized fan housing of the system of FIG. 1.

FIG. 9 is a perspective view from the back, outlet end of the detachablemotorized fan housing system of FIG. 1.

FIG. 10 is a perspective view of a main primary air filer element usedin the system of FIG. 1.

FIG. 11 is a perspective view of a secondary safety air filter elementoptionally used in the system of FIG. 1 inside of the main primary airfilter element.

FIG. 12 is a perspective view of the filter housing from the front endwith no filter installed therein.

FIG. 13 is a perspective view of the filter housing from the back,outlet end thereof with no filter installed.

FIG. 14 is a perspective view of the filter housing like FIG. 12 butwith the optional safety filter installed.

FIG. 15 is a perspective view of the filter housing like FIG. 13 butwith the main filter shown installed therein.

FIG. 16 is a perspective view from the back, outlet end, and to oneside, of a second example embodiment of the air cleaningsystem/apparatus of the invention wherein the filter housing has a solidrear panel about the clean air outlet and an outer cylindrical wall,with a long ejection slot the length of the air filter.

FIG. 17 is a schematic, cross-sectional view taken at a right angle tothe axis A-A of either of the disclosed embodiments, showing theprovision of a debris strake connected to the air filter and extendingthe length of the filter to help channel the debris in the rotating flowof debris laden air away from the filter to the outer wall of the filterhousing.

BEST MODE FOR CARRING OUT THE INVENTION

Referring now to the drawings, a powered air cleaning system orapparatus 1, FIGS. 1-6, according to a first example embodiment is shownconnected to the air intake 29 of a device 28, such as an internalcombustion engine or other device requiring a supply of clean air, asshown schematically in FIG. 2. The system comprises a flow path 22extending through the system from an air inlet 4 to a clean air outlet 5which supplies clean air to the air intake 29 of device 28. The flowpath is located within a generally cylindrical housing 23 of the system.Housing 23 is formed by two detachable components—motorized fan housing2 and filter housing 3 which are detachably connected to one another ata service flange assembly 6 by joining clips 7, see FIG. 7. For thispurpose each of the housings 2 and 3 has a joining flange, 16 and 17,respectively. The housings 2 and 3 are shown detached from one anotherin FIG. 6 and shown separately in FIGS. 8 and 9, and 12 and 13,respectively.

A motor-driven fan 24, comprising a fan blade 10 mounted on the outputshaft of an electric motor 13, is located along the flow path 22 to drawparticulate debris laden air into the inlet 4 and rotate it about anaxis A-A to form a rotating flow in the system that stratifies thedebris laden air with the heaviest particles in the outermost orbits ofthe rotating flow. A compression assembly 11 in the form of an angledlouver/motor mount assembly with fixed louvers or vanes 12 is locatedwithin the fan housing 2 downstream of the fan blade 10. The compressionassembly compresses the volume of the rotating flow of debris laden airdrawn into the system inlet to increase the air velocity and centrifugalforce acting on the airborne articles. The motor-driven fan 24 issupported at motor 13 thereof within the fan housing by way of the anglelouver/motor mount assembly 11 as seen in FIGS. 3, 4, 8 and 9.

A separator-ejector chamber 18 is provided in the flow path of the aircleaning system downstream of the angled louver/motor mount assembly,FIGS. 3-6, 9 and 15. The outermost orbits of the rotating flow patternof debris laden air ride on the outer wall 27 of the separator-ejectorchamber until reaching an annular ejector port 25 formed about theoutlet 5 in the outlet end of the housing radially outward of the cleanair outlet. The ejector port is formed by a series of circumferentialradial ejection slots 8 separated by strakes 15. The ejector port ejectsparticulate debris laden air from the stratified rotating flow in thesystem to the environment.

An air filter 9, FIGS. 2-4, 6 and 15, in the form of a filter package ofat least a main primary air filter element 20, FIGS. 10 and 15, andoptionally a secondary safety air filter element 21, FIGS. 11 and 14,located within the filter element 20, is located within the rotatingflow and across the flow path upstream of the outlet for filtering airfrom the innermost orbits of the stratified rotating flow in the systemas the air flows to the clean air outlet 5. The filter 9 is elongated inthe direction of and extends along the central longitudinal axis A-A ofthe generally cylindrical housing 23 in the separator-ejector chamberfrom the outlet end, where it is mounted on clean air outlet orifice 19,FIG. 5. The upstream end of the filter 9 is supported by a filtercompression bracket 14 connected to a support flange 30, FIG. 9, on theend of motor 13.

Debris buildup on the outer surface of the filter 9 is minimized bylocating the filter within the rotating flow of the debris laden air inthe separator-ejector chamber 18 and by returning particulate debrisladen air from the stratified rotating flow in chamber 18 unrestrictedthrough the ejector port 25 at the end of the chamber, e.g., withoutdisrupting the stratified rotating flow in the chamber. The selfcleaning action on the filter 9 has also been found to be enhanced, insupplying air to the air intake 29 of a device 28 having a cyclic airflow demand, such as an internal combustion engine which applies avariable vacuum to the outlet 5 of the system, by operating themotor-driven fan to maintain positive air flow pressure on the outersurface of the filter and to return debris laden air to the environmentfrom the system at all rates of air flow demanded by the device. The aircleaning system 1 is designed to generate a much larger air flow thanthe engine or apparatus 28 upon which it is installed requires, therebyproviding a consistent positive air flow pressure to the filter keepingdebris buildup on the air filter to a minimum and providing a powerfulair flow out of the 360° ejection port 25 formed by the series of radialejection slots 8 located at the end of the separator-ejector chamber.

The air cleaning system and air cleaning method of the invention make itpossible to maintain low air filter restriction throughout normalservice intervals for internal combustion engines and other apparatus bysignificantly extending air filter life over current service intervals.While the air cleaning system and air cleaning method have beendescribed specifically for use in supplying clean air to an internalcombustion engine, the invention is not limited to such a use but haswide application for a variety of devices requiring a supply of cleanair including ventilation systems, heat exchangers, air compressors, andheating and air conditioning systems.

A second example embodiment of the powered air cleaning system orapparatus 31 of the invention shown in FIG. 16 is like the system orapparatus 1 of the first example embodiment except for the filterhousing, 32 in FIG. 16. That is, instead of providing the ejector portin the outlet end of the filter housing radially outward of the cleanair outlet as in the first example embodiment, in the filter housing 32the ejector port 33 is located radially outward of the outermost orbitsof the rotating flow opposite the air filter. In particular, the ejectorport 33 is in the form of a slot in the outer wall of theseparator-ejector chamber of the filter housing, the slot extending thelength of the air filter. The outlet end of the housing 32 has a solidpanel, e.g. is closed, about the clean air outlet 5.

Thus, instead of the debris being allowed to stay in its stratifiedstate for the length of the housing until it is ejected at the rear ofthe system or apparatus as in the first example embodiment, in thesystem or apparatus 31 with filter housing 32, as the debris hits theouter orbits of the separation pattern, it is immediately ejected fromthe rotating flow and the system or apparatus through the ejector slot33. This feature facilitates directing the debris away from the systemor apparatus and channeling the debris away from the device, such as aninternal combustion engine, on which the system or apparatus isinstalled. The air filter within the filter housing 32 can alsoadvantageously be subjected to the slight positive pressure during use,reducing restriction to the engine or other device on which the systemor apparatus is installed.

Another feature of the invention shown in FIG. 17 can be used with eachof the example embodiments. This involves the provision of a debrisstrake 34 on the outer periphery of the air filter 9. The strake 34extends longitudinally the length of the air filter and extendsoutwardly from the outer periphery of the filter in a direction of therotating flow, shown by arrow B in FIG. 17, for channeling debris in therotating flow adjacent the air filter away from the filter to theoutermost orbits of the rotating flow for ejection from the system.

While we have shown and described only two embodiments in accordancewith the present invention, it is understood that the same is notlimited thereto, but is susceptible to numerous changes andmodifications as known to the skilled in the art. For example, thepowered air cleaning systems of the invention can be used without theair filter 9 to supply air to a device where centrifugal separation ofdebris from debris laden air and withdrawal of air from the innermostorbits of the rotating flow in the system by a vacuum from the device atthe outlet of the system provides satisfactory cleaning. In this regard,it is noted that the positive pressure in the device maintains flowthrough the ejector port of the system while the pressure at the cleanair outlet remains essentially neutral, with or without air filter 9.The device draws clean air from the clean air outlet in accordance withits demand, e.g., vacuum pull applied to the clean air outlet of thesystem. Therefore, we do not wish to be limited to the details shown anddescribed herein, but instead to cover all such changes andmodifications as are encompassed by the scope of the appended claims.

1. A powered air cleaning system comprising: a flow path extendingthrough the system from an inlet to an outlet; a motor-driven fanlocated along the flow path to draw particulate debris laden air intothe inlet and rotate it about an axis to form a rotating flow thatstratifies the debris laden air with the heaviest particles in theoutermost orbits of the rotating flow; an ejector port for ejectingparticulate debris laden air from the stratified rotating flow in thesystem; and an air filter located within the rotating flow and acrossthe flow path upstream of the outlet for filtering air from theinnermost orbits of the stratified rotating flow, the air filter beingelongated in the direction of the axis about which the debris laden airis rotated; wherein the ejector port is located radially outward of theoutermost orbits of the rotating flow.
 2. The air cleaning systemaccording to claim 1, wherein the filter is located centrally within aseparator-ejector chamber in the flow path of the air cleaning system.3. The air cleaning system according to claim 1, wherein the ejectorport is elongated in a direction along the length of the elongatedfilter.
 4. The air cleaning system according to claim 1, wherein anouter peripheral surface of the elongated filter is cylindrical.
 5. Theair cleaning system according to claim 1, further comprising acompression assembly for compressing the volume of the rotating flow ofdebris laden air to increase the air velocity and centrifugal forceacting on the airborne particles.
 6. The air cleaning system accordingto claim 5, wherein the compression assembly provides support for themotor-driven fan.
 7. The air cleaning system according to claim 5,wherein the compression assembly includes a plurality of stationaryvanes in the flow path.
 8. The air cleaning system according to claim 5,further comprising a separator-ejector chamber in the flow pathdownstream of the compression assembly, the outermost orbits of therotating flow riding on an outer wall of the separator-ejector chamber,the ejector port being located in the outer wall of the separatorejector chamber.
 9. The air cleaning system according to claim 8,wherein said filter is located centrally within said separator-ejectorchamber.
 10. The air cleaning system according to claim 1, furthercomprising a generally cylindrical housing, said inlet and said outletbeing arranged at respective ends of said housing and said flow pathextending through housing.
 11. The air cleaning system according toclaim 10, wherein said ejector port is arranged in a generallycylindrical outer wall of the housing radially outward from the airfilter.
 12. The air cleaning system according to claim 11, wherein saidfilter extends along a central longitudinal axis of the generallycylindrical housing from the outlet end thereof and the ejector port isin the form of an ejector slot which extends the length of the airfilter.
 13. The air cleaning system according to claim 12, furthercomprising a bracket for supporting within the housing an end of thefilter remote from the outlet end of the housing.
 14. The air cleaningsystem according to claim 1, further comprising a debris strakeconnected to the air filter for channeling debris away from the filterto the outermost orbits of the rotating flow.
 15. A powered air cleaningsystem for use with a device having a variable air flow demand, thesystem comprising: a flow path extending through the system from aninlet to an outlet for supplying air to the device; a motor-driven fanlocated along the flow path to draw particulate debris laden air intothe inlet and rotate it about an axis to form a rotating flow thatstratifies the debris laden air with the heaviest particles in theoutermost orbits of the rotating flow; an ejector port for ejectingparticulate debris laden air from the stratified rotating flow in thesystem; an air filter located within the rotating flow and across theflow path upstream of the outlet for filtering air from the innermostorbits of the stratified rotating flow; a debris strake connected to theair filter for channeling debris away from the filter to the outermostorbits of the rotating flow; wherein the motor-driven fan is operable tomaintain positive air flow pressure to eject debris laden air from thestratified rotating flow in the system at all rates of air flow demandedby the device.
 16. The air cleaning system according to claim 15,wherein the device with a variable air flow demand is an internalcombustion engine which exerts a variable vacuum on the outlet of thesystem by way of the air intake of the engine.
 17. An air cleaningmethod comprising: drawing particulate debris laden air into an aircleaning system with a motor-driven fan located in the system; forming arotating flow of the debris laden air in the system to stratify the flowwith the heaviest particles in the outermost orbits of the rotatingflow; flowing air from the innermost orbits of the rotating flow througha filter enroute to an outlet of the system, the filter being locatedwithin the rotating flow which provides a self cleaning action on thefilter; channeling debris away from the filter to the outermost orbitsof the rotating flow with a debris strake connected to the filter; andejecting particulate debris laden air from the stratified rotating flowin the system.
 18. The method according to claim 17, wherein saidejecting is performed without disrupting the stratified rotating flow inthe system.
 19. The method according to claim 17, wherein said ejectingincludes flowing stratified rotating flow through an ejector portlocated radially outward of the outermost orbits of the rotating flowopposite the filter.
 20. The method according to claim 17, for use insupplying air to a device with a variable air flow demand which appliesa variable vacuum to the outlet of the air cleaning system, the methodfurther including operating the motor-driven fan to maintain positiveair flow pressure to eject particulate debris laden air from therotating flow in the system at all rates of air flow demand by thedevice and to allow buildup of debris on the filter to be removed atleast during low rates of air flow demand.
 21. The method according toclaim 20, wherein the device is an internal combustion engine which issupplied air from the outlet of the system.
 22. An air cleaning methodcomprising: drawing particulate debris laden air into an air cleaningsystem with a motor-driven fan located in the system; forming a rotatingflow of the debris laden air in the system at a positive air flowpressure to stratify the flow with the heaviest particles in theoutermost orbits of the rotating flow; ejecting particulate debris ladenair from the outermost orbits of the stratified, positively pressuredrotating flow in the system through an ejector port located radiallyoutward of the outermost orbits of the rotating flow; and withdrawingair from the innermost orbits of the rotating flow in the system throughan air filter and an outlet of the system by applying a vacuum to theoutlet, wherein the air filter is swept by the rotating flow to providea self cleaning action on the filter.
 23. The method according to claim22, including operating the motor-driven fan to maintain the positiveair flow pressure to eject particulate debris laden air from theoutermost orbits of the stratified rotating flow in the system at allrates of withdrawal of air through the outlet of the system.
 24. Themethod according to claim 22, wherein the ejector port is in the form ofa slot in a housing containing the rotating flow, the slot extending ina direction transverse to the direction of rotation of the rotatingflow.